Black Tern

Chlidonias niger

A small, graceful marsh tern, black and silver in breeding plumage. In its choice of surroundings, it leads a double life: in North America in summer it is a typical bird of freshwater marshes, but in winter it becomes a seabird along tropical coasts. Vulnerable to loss of marsh habitat, its numbers have decreased in many areas during recent decades.

Conservation status

North American population has declined sharply since the 1960s. Loss of nesting habitat owing to drainage of wetlands is one likely cause. Runoff of farm chemicals into nesting marshes may affect hatching success. Loss of food supply on the wintering grounds, owing to local overfishing, may also be a factor.

Fresh marshes, lakes; in migration, coastal waters. For nesting favors fresh waters with extensive marsh vegetation and open water, also sometimes in smaller marshes and wet meadows. In migration found on larger lakes and along coast. Winters in tropical coastal regions, mostly just offshore or around salt lagoons and estuaries.

A small, graceful marsh tern, black and silver in breeding plumage. In its choice of surroundings, it leads a double life: in North America in summer it is a typical bird of freshwater marshes, but in winter it becomes a seabird along tropical coasts. Vulnerable to loss of marsh habitat, its numbers have decreased in many areas during recent decades.

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Feeding Behavior

Forages in flight, dipping to surface of water or shore to pick up items, sometimes pursuing flying insects in the air, seldom plunging into water after prey.

Eggs

2-4. Pale buff to olive, blotched with brown and black. Incubation is by both sexes, 21-22 days. Young: Develop rapidly; after 2-3 days, may leave nest but remain in vegetation nearby. Capable of flight 19-25 days after hatching; may be fed by parents for up to two more weeks. One brood per year, sometimes two in south.

Young

Develop rapidly; after 2-3 days, may leave nest but remain in vegetation nearby. Capable of flight 19-25 days after hatching; may be fed by parents for up to two more weeks. One brood per year, sometimes two in south.

Diet

Mostly insects, fish. Diet on breeding grounds is mostly insects, also small fish, tadpoles, frogs, spiders, earthworms, crustaceans, leeches. In migration and winter at sea, eats mostly small fish, also some crustaceans and insects.

Nesting

Breeds in scattered colonies, often associated with Forster's Terns. Early in season, pairs or small groups ascend in spiraling high flight above colony, then glide down. Nest site is low in marsh, on floating mat of plant material, on old muskrat house or debris, or on ground close to water. Nest (built by both parents) may be substantial platform of marsh plants, or simple depression with a few bits of vegetation added, very close to water level; eggs often damp.

Migration

Most apparently migrate north through interior of North America. In late summer, many move east to Atlantic Coast before turning south; those from farther west may move south to coasts of Mexico and continue southward offshore. Winters mostly along north and northwest coasts of South America.

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Migration

Most apparently migrate north through interior of North America. In late summer, many move east to Atlantic Coast before turning south; those from farther west may move south to coasts of Mexico and continue southward offshore. Winters mostly along north and northwest coasts of South America.

How climate change could affect this bird's range

In the broadest and most detailed study of its kind, Audubon scientists have used hundreds of thousands of citizen-science observations and sophisticated climate models to predict how birds in the U.S. and Canada will react to climate change.

Black Tern

Each map is a visual guide to where a particular bird species may find the climate conditions it needs to survive in the future. We call this the bird’s “climatic range.”

The colors indicate the season in which the bird may find suitable conditions— blue for winter, yellow for summer (breeding), and green for where they overlap (indicating their presence year-round).

The darker the shaded area, the more likely it is the bird species will find suitable climate conditions to survive there.

The outline of the approximate current range for each season remains fixed in each frame, allowing you to compare how the range will expand, contract, or shift in the future.

The first frame of the animation shows where the bird can find a suitable climate today (based on data from 2000). The next three frames predict where this bird’s suitable climate may shift in the future—one frame each for 2020, 2050, and 2080.

You can play or pause the animation with the orange button in the lower left, or select an individual frame to study by clicking on its year.

The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season. More on reading these maps.

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